A number of routes and manufacturing processes exist for making light guide layers suitable for use in backlighting applications. Typically, a transparent polymer is injection moulded to form a thin plate with suitable surface features. The surface features disturb the total internal reflection of the light thus allowing light, guided inside the plate, to escape in a controlled manner.
However, there are a number of problems associated with such a technique, not least the expense associated with forming a suitable mould. Typically, the mould is machined or laser cut. Once the mould has been formed, the optical parameters are, effectively, fixed.
Other techniques for forming light guide layers include microstamping or hot embossing polymer sheets. However, the optical quality associated with such polymer sheets is limited by the stamp quality and the associated manufacturing process.
Particularly as backlights become larger, these limitations become more critical. In this regard, there is a continued need for alternative and/or improved light guide layers and structures and methods for formation thereof for use in, inter alia, backlighting applications.
The present invention is partly based on the finding that microstructured optical films, which may be commercially available, may be suitably modified with ink to render them suitable for use in light guide plates and backlighting applications.